Virtual decoupling to break the simplification versus resolution trade-off in nuclear magnetic resonance of complex metabolic mixtures

The heteronuclear single quantum correlation (HSQC) experiment developed by Bodenhausen and Ruben (1980) in the early days of modern nuclear magnetic resonance (NMR) is without a doubt one of the most widely used experiments, with applications in almost every aspect of NMR including metabolomics. Acquiring this experiment, however, always implies a trade-off: simplification versus resolution. Here, we present a method that artificially lifts this barrier and demonstrate its application towards metabolite identification in a complex mixture. Based on the measurement of clean in-phase and clean anti-phase (CLIP/CLAP) HSQC spectra (Enthart et al., 2008), we construct a virtually decoupled HSQC (vd-HSQC) spectrum that maintains the highest possible resolution in the proton dimension. Combining this vd-HSQC spectrum with a J-resolved spectrum (Pell and Keeler, 2007) provides useful information for the one-dimensional proton spectrum assignment and for the identification of metabolites in Dreissena polymorpha (Prud'homme et al., 2020).

Virtual decoupling to break the Simplification Versus Resolution Trade Off in NMR of Complex Metabolic Mixtures

The HSQC experiment developed by Bodenhausen and Ruben (Bodenhausen and Ruben, 1980) in the early days of modern NMR is without a doubt one of the most widely used experiments, with applications in almost every aspect of NMR including metabolomics. Acquiring this experiment however always implies a trade-off: simplification versus resolution. Here, we present a method that artificially lifts this barrier, and demonstrate its application towards metabolite identification in a complex mixture. Based on the measurement of CLean In-Phase and CLean Anti-Phase (CLIP/CLAP) HSQC spectra (Enthart et al., 2008), we construct a virtually decoupled HSQC (vd-HSQC) spectrum that maintains the highest possible resolution in the proton dimension. Combining this vd-HSQC spectrum with a J-resolved spectrum (Pell and Keeler, 2007) provides useful information for the one-dimensional proton spectrum assignment and for the identification of metabolites in Dreissena polymorpha (Prud’homme et al., 2020).

Fresh insights on properties of particle fluxes in cosmic rays measured with the Alpha Magnetic Spectrometer on the international space station

The Alpha Magnetic Spectrometer is a particle physics detector focusing on the search for dark matter, the existence of antimatter, the origin and composition of cosmic rays from primordial sources in the universe and the exploration of new physics in space. Important features of the elementary particle (proton, antiproton, positron and election) fluxes in cosmic rays are presented: (1) The proton spectrum has a smooth hardening from 200 GeV; (2) antiproton and positron spectra show excess from traditional physics background; (3) in particular, the positron flux shows a source term with a cutoff energy of 810 GeV, which raises the question of its source; (4) the origin of the energetic electrons is different from that of positrons and (5) the identical momentum dependence of primary and secondary cosmic ray nuclei fluxes are also reviewed.

Study on the Diagnostic Value of Magnetic Resonance Imaging in Patients with Malignant Glioma

Objective: To explore the value of multi-voxel-based monomer 1H-MRS (magnetic resonance imaging) in the classification of gliomas. Methods: 26 gliomas confirmed by surgery and pathology were examined by conventional MRI, multi-voxel 2D, and monomer 1H-MRS before surgery. Three types of regions of interest (ROI) were used to measure Cho/NAA (Choline hydroxide solution/N-acetyl aspartic acid) values in the tumor. Methods: In the multi-voxel 2D hydrogen proton spectrum, the solid part of the tumor or the most intensive region of the tumor was selected to determine the Cho/NAA value. At the same time, in the multi-voxel 2D hydrogen proton spectrum, the Fun/tool spectra's copy-2DBmin analysis software was used to obtain the Cho/NAA value distribution. Anatomically superimposed the pseudo-color image, and measure the Cho/NAA value in its largest Cho/NAA value region. In addition, based on the level set algorithm, it uses the Otsu algorithm to initially locate the edema area and provide the initial contour. Results: The Cho/NAA values measured by the ROI selection method were statistically significant, and the sensitivity and specificity of judging the benign and malignant gliomas indicated that Method 3 had the highest diagnostic value. Conclusion: Multi-voxel-based monomeric 1H-MRS magnetic resonance imaging has the highest value in guiding glioma classification and can improve the accuracy of glioma classification.